Ironically, I'm not as confident with my GX7's interface as my Olympus cameras' interfaces. It's purely down to how comfortable my own brain is with the two approaches, I think. It's not them, it's me!
I don't think this generalization is valid.
There are consumer electronics or computer programs/software that are easy to use, because everything seems logically and works as one would expect. This is not the case with the Oly menu system. One example is setting the size of the focus box:
On Panasonic (e.g. GH4), you can either go to the AF menu (dedicated button) and follow the on-screen instructions (pressing the down arrow) to get to the AF box size menu and resize using the control wheel or just tapping on the screen and see the same menu to move/resize the same AF box. There is no question mark in my mind when following this, it's a plain simple procedure.
On the E-M5II (or any other Olympus), I would also (following simple logic) go to the AF menu in the SCP, click on the Info button to change AF fields and ... that's it. I cannot change the size of the AF field here no matter what I do. All you can do is switch through the 4 different AF types. But you cannot modifiy or move the size of the AF box here in the actual AF menu.